A modified Bessel filter for amplitude demodulation of respiratory electromyograms.
We studied a device that is commonly used for amplitude demodulation of respiratory muscle electromyograms (EMG). This device contains a rectifier and a low-pass filter called a modified third-order Paynter filter. We characterized this filter and found that it has good transient characteristics that suit its task as an EMG demodulator, but it has poor high-frequency attenuation that passes interfering, higher frequency components to the output waveform. Therefore, we designed and constructed a new filter with transient characteristics that are comparable to those of the modified Paynter filter but with superior high-frequency attenuation. This new filter is a modified seventh-order Bessel filter. We also identified a simple technique to convert an existing modified Paynter filter back to an original Paynter filter. The original Paynter filter has a wider pass band than the modified Paynter filter but superior stop-band attenuation.
Platt
R S
RS
Department of Medicine, University of Calgary, Alberta, Canada.
Hajduk
E A
EA
Hulliger
M
M
Easton
P A
PA
D004562:Electrocardiography; D004576:Electromyography / Q000295:instrumentation*; D004581:Electronics / Q000295:instrumentation*; D006801:Humans; D017933:Peripheral Nervous System / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology*